• Radiation Oncology Journal
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• v.21 no.1
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• pp.1-9
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• 2003

Purpose : The purpose of this study was to analyze the effect of a Linear accelerator based Photon Knife Radiosurgery System developed by the staff of Keimyung University Dongsan Medical Center for the treatment of cerebral arterlovenous malformation Material and Methods : Between December 1993 and October 2000, 30 patients with cerebral arteriovenous malformation (AVM) were treated with the Linac based Photon knife Radlosurgery System In the Department of Therapeutlc Radiology at Keimyung University Dongsan Medical Center. The median age was 34, ranging from 7 to 63 years, with a 2 : 1 male to female ratio. The locations of the AVM nidi were the frontal lobe (motor cortex), parletal lobe, and the thalamus, In that order. The diameters of the AVM nidi ranged 1.2 to 5.5 cm with a mean on 2.9 cm, and target volumes of between 0.5 and 20.5 cc, with a mean of 5.8 cc. The majority of patients received radiation doses of between 1,500 and 2,500 cGy, w14h a mean of 2,000 cGy, at 80% the isodose line. Twenty-five patients were treated with one isocenter, 4 with two, and 1 with four. The follow-up radiological evaluations were peformed with cranial computed tomogram (CT) or MRI between 6 month and one year interval, and if the AVM nidus had completely disappeared in the CT or MRI, we confirmed thls was a complete obliteration, with a cerebral or magnetic resonance angiogram (MRA). The median iollow-up period was 39 months with a range of 10 to 103 months. Results : Twenty patients were radloiogicaiiy followed up ior over 20 months, with complete obliteration observed in 14 (70%). According to the maximal diameter, all four of the small AVM (<2 cm) completely obliterated, 8 of the 10 patients with a medium AVW (2~3 cm) showed a complete obliteration, and two showed partial obliteration. Among the patients with a large AVM (>3 cm), only one showed complete obliteration, and S showed partial obliteration, but 3 oT these underwent further radiosurgery 3 years later. One who followed up for 20 months fellowing further radiosurgery eventually showed complete obliteration. Ten patients with seizure symptoms had no recurrent seizure due to radiosurgery and medication. One of the eleven patients who suffered intracranlal bleeding developed further bleeding at 9 and 51 months fellowing the radiosurgery although complete obliteration was eventually observed and the patient was managed in hospital then recovered. No patient suffered severe complications fellowing the radiosurgery. Conclusion : The radiosurgery with Linac-based Photon knife radiosurgery system, developed by the staff at our hospital, is a safe and effective treatment for AVM patients having diameters or volumes of less than 3 cm or 10 cm$^{3}$, respectively, located In Inoperable areas or who refused neurosurgery. We suggest that staged AVM radiosurgery may initially be considered, if the AVM target volume is above 10 cm$^{3}$

• Journal of the Korean Society of Radiology
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• v.81 no.3
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• pp.676-687
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• 2020

Purpose To analyze the altered brain regions and intrinsic brain activity patterns in trauma-exposed firefighters without posttraumatic stress disorder (PTSD). Materials and Methods Resting-state functional MRI (rsfMRI) was performed for all subjects. Thirty-one firefighters over 40 years of age without PTSD (31 men; mean age, 49.8 ± 4.7 years) were included. Twenty-six non-traumatized healthy controls (HCs) (26 men; mean age, 65.3 ± 7.84 years) were also included. Voxel-based morphometry was performed to investigate focal differences in the brain anatomy. Seed-based functional connectivity analysis was performed to investigate differences in spontaneous brain characteristics. Results The mean z-scores of the Seoul Verbal Learning Test for immediate and delayed recall, Controlled Oral Word Association Test (COWAT) score for animals, and COWAT phonemic fluency were significantly lower in the firefighter group than in the HCs, indicating decreased neurocognitive function. Compared to HCs, firefighters showed reduced gray matter volume in the left superior parietal gyrus and left inferior temporal gyrus. Further, in contrast to HCs, firefighters showed alterations in rsfMRI values in multiple regions, including the fusiform gyrus and cerebellum. Conclusion Structural and resting-state functional abnormalities in the brain may be useful imaging biomarkers for identifying alterations in trauma-exposed firefighters without PTSD.

• Progress in Medical Physics
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• v.21 no.1
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• pp.70-77
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• 2010

This study tested how S/N (Signal to Noise Ratio) ratios and ADC (apparent diffusion coefficient) values vary with different T-scores in a group of patients with osteoporosis. Based on DEXA (Dual Energy X-ray Absorptiometry) T-scores for L1.L4 for two groups of subjects consisting of 30 healthy people without osteoporosis and 30 patients who came for treatment of waist (lumbar or low back) pain and were suspected to have osteoporosis as judged from the simple X-ray findings, this study classified every spine into two groups of osteoporosis and osteopenia. Signal intensity measurements were made in the four regions of L1 to L4 on diffusion-weighted MR images obtained using 1.5T MR scanner, while ADC measurements were obtained from ADC map images. As an approach for quantitative analysis, the comparison of the variances in S/N ratios and ADC values for varying T-scores in the selected regions of interest was carried out based on averaged T-scores, S/N ratios, and ADC values. Also, the variances in S/N ratios and ADC values for each of the groups of osteoporosis and osteopenia, which were classified into by T-scores, were compared. For qualitative analysis, a careful naked eye examination of signal intensity differences in the area of L4 was made on T1-weighted sagittal images for each of the healthy (normal), osteopenia, and osteoporosis groups. In the qualitative analysis, it was found that for both the osteopenia group and the osteoporosis group, as T-scores deceased, the S/N ratios on diffusion-weighted MR images also decreased, with the greatest decrease in the S/N ratio found in the osteoporosis group. Additionally, among the three groups, the lowest S/N ratio was found in the osteoporosis group. With respect to ADC map, it was found that for both the osteopenia group and the osteoporosis group, as T-scores deceased, the ADC values on diffusion-weighted MR images also decreased, with the greatest decrease in the ADC values found in the osteoporosis group. Additionally, among the three groups, the lowest ADC value was found in the osteoporosis group. On the other hand, in the qualitative analysis, the osteoporosis group showed the highest signal intensity. Additionally, among the three groups, the lowest signal intensity was found in the healthy (normal) group. It was found that as osteoporosis progressed, S/N ratio and ADC decreased, whereas signal intensity increased on T1-weighted images. Also, in diagnosing osteoporosis, MRI tests turned out to be (more) effective.

• Journal of the Korean Society of Radiology
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• v.5 no.6
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• pp.315-324
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• 2011

The purpose of this study was to use as basic data for the is systematic and efficient facility inventory of policeman and the riot police, conscripted policeman. First, the analysis was performed for the patient implementing the simple x-ray, CT, and MRI examination to the policeman and the riot police, conscripted policeman within the radiologic examination. As to the classification by disease, it classified into the partial body as the common disease and musculoskeletal system disease. As to the fixed quantity comparison of the policeman and the riot police, conscripted policeman the basic X-ray, CT, MRI examination by part average personnel was compared. As to the research result the riot police, conscripted policeman, the Lower extremity examination occupies the simple X-ray, CT, and MRI examination in comparison with the other part altogether much and particularly, the Knee examination ratio occupies much among the Lower extremity examination.

• Progress in Medical Physics
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• v.20 no.4
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• pp.235-243
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• 2009

The purpose of this experiment is to know the relation of the detection and characterization of liver's diseases as comparison of finding at MR imaging using a Ferucarbotran (SPIO) and Gd-EOB-DTPA (Primovist) agents in diffuse liver disease. A total of 50 patients (25 men and 25 women, mean age: 50 years) with liver diseases were investigated at 3.0T machine (GE, General Electric Medical System, Excite HD) "with 8 Ch body coil for comparison of diseases and contrast's uptake relation, which used the LAVA, MGRE." All images were performed on the same location with before and after Ferucarbotran and Gd-EOB-DTPA administrations (p<0.05). Contrast to noise ratio of Ferucarbotran and Gd-EOB-DTPA in the HCC were $3.08{\pm}0.12$ and $7.00{\pm}0.27$ with MGRE and LAVA pulse sequence, $3.62{\pm}0.13$ and $2.60{\pm}0.23$ in the hyper-plastic nodule, $1.70{\pm}0.09$ and $2.60{\pm}0.23$ in the meta, $2.12{\pm}0.28$ and $5.86{\pm}0.28$ in the FNH, $4.45{\pm}0.28$ and $1.73{\pm}0.02$ in the abscess and ANOVA test was used to evaluate the diagnostic performance of each disease (p<0.05). In conclusions, two techniques were well demonstrated with the relation of the detection and characterization of liver's diseases.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.235-243
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• 2000

Magnetic resonance imaging(MRI) of the temporomandibular joint(TMJ) is very useful method to diagnose internal derangement of the TMJ because of its high specificity foy identification of condyle-disc relationships. The purpose of this study was to evaluate the existence, incidence and severity o』 internal derangement o』 the TMJ by the MRI of Patients who are suspected to have TMJ disorder. MRI sample was composed of 50 subjects(10 males, 40 females) and the mean age was 22.9 years. 43 subjects of the sample were found to have positive findings. $56\%$ of the subjects with positive findings had ADD(anterior disc displacement) without reduction, and $65\%$ had internal derangement of bilateral joints. Distributions in the types of malocclusion in patients with positive findings, the Angle's classification had shown : the largest $41.9\%$ for Cl II ($39.6\%$ for Cl II div 1 and $2.3\%$ for Cl II div 2), $37.2\%$ for Cl I, $18.6\%$ for Cl III, and $2.3\%$ for the unidentified. $8.6\%$ of the subjects with positive findings had facial asymmetry and $55.8\%$ had openbite. We can conclude that the percentage of Cl II is the highest in patients with internal derangement of the TMJ. Openbite or facial asymmetry is considered to be uncompensated or compensated deformity which results from facial skeleton remodeling in the process of degenerative joint disease(DJD) due to TMJ degeneration. Therefore it is recommended to screen the patients with facial asymmetry or openbite by MRI before the beginning of orthodontic treatment. Differential diagnosis is essential because the tendency of relapse is high after the orthodontic treatment and continuous observation of TMJ is needed in patients with TMJ disorder.

• Progress in Medical Physics
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• v.26 no.4
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• pp.193-200
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• 2015

The aim of this study is to present commissioning results of the ViewRay system. We verified safety functions of the ViewRay system. For imaging system, we acquired signal to noise ratio (SNR) and image uniformity. In addition, we checked spatial integrity of the image. Couch movement accuracy and coincidence of isocenters (radiation therapy system, imaging system and virtual isocneter) was verified. Accuracy of MLC positioing was checked. We performed reference dosimetry according to American Association of Physicists in Medicine (AAPM) Task Group 51 (TG-51) in water phantom for head 1 and 3. The deviations between measurements and calculation of percent depth dose (PDD) and output factor were evaluated. Finally, we performed gamma evaluations with a total of 8 IMRT plans as an end-to-end (E2E) test of the system. Every safety system of ViewRay operated properly. The values of SNR and Uniformity met the tolerance level. Every point within 10 cm and 17.5 cm radii about the isocenter showed deviations less than 1 mm and 2 mm, respectively. The average couch movement errors in transverse (x), longitudinal (y) and vertical (z) directions were 0.2 mm, 0.1 mm and 0.2 mm, respectively. The deviations between radiation isocenter and virtual isocenter in x, y and z directions were 0 mm, 0 mm and 0.3 mm, respectively. Those between virtual isocenter and imaging isocenter were 0.6 mm, 0.5 mm and 0.2 mm, respectively. The average MLC positioning errors were less than 0.6 mm. The deviations of output, PDDs between mesured vs. BJR supplement 25, PDDs between measured and calculated and output factors of each head were less than 0.5%, 1%, 1% and 2%, respectively. For E2E test, average gamma passing rate with 3%/3 mm criterion was $99.9%{\pm}0.1%$.

• Korean Journal of Cognitive Science
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• v.33 no.2
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• pp.109-133
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• 2022

Episodic memory consists of a core event and the associated contexts. Although the role of the hippocampus and its neighboring regions in contextual representations during encoding has become increasingly evident, it remains unclear how these regions handle various context-specific information other than spatio-temporal contexts. Using high-resolution functional MRI, we explored the patterns of the medial temporal lobe (MTL) and cortical regions' involvement during the encoding of various types of contextual information (i.e., journalism principle 5W1H): "Who did it?," "Why did it happen?," "What happened?," "When did it happen?," "Where did it happen?," and "How did it happen?" Participants answered six different contextual questions while looking at simple experimental events consisting of two faces with one object on the screen. The MTL was divided to sub-regions by hierarchical clustering from resting-state data. General linear model analyses revealed a stronger activation of MTL sub-regions, the prefrontal lobe (PFC), and the inferior parietal lobule (IPL) during social (Who), behavioral (How), and intentional (Why) contextual processing when compared with spatio-temporal (Where/When) contextual processing. To further investigate the functional networks involved in contextual encoding dissociation, a multivariate pattern analysis was conducted with features selected as the task-based connectivity links between the hippocampal subfields and PFC/IPL. Each social, behavioral, and intentional contextual processing was individually and successfully classified from spatio-temporal contextual processing, respectively. Thus, specific contexts in episodic memory, namely social, behavior, and intention, involve distinct functional connectivity patterns that are distinct from those for spatio-temporal contextual memory.

• Investigative Magnetic Resonance Imaging
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• v.11 no.1
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• pp.27-32
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• 2007

Purpose : To evaluate the mucoid degeneration (MD) of the anterior cruciate ligament (ACL) of the knee by correlation of MRI findings with pathology, in the patients with osteoarthritis (OA). Materials and Methods : This study included 17 patients (mean 68.8 years old) who underwent preoperative MRI. In proton density-weighted sagittal and coronal images ACLs were evaluated for the thickness and signal intensity (SI). Total knee replacement arthroplasty was performed and the pathologic findings of ACL were evaluated. MD was classified as 3 grades according to the degenerated amount in microscopy. Thickness and SI was evaluated as normal or increased on MRI. Results : All of the 4 patients who showed thickened ACL showed increased SI on MRI. All of the 8 patients with increased SI of the ACL on MRI had MD in the ACL. However, remained 9 patients also had MD, in spite of their normal thickness and SI on MRI. Calcification was seen in 5 patients. Conclusion : Eight cases who showed ACL thickening or increased SI on MRI were well correlated with MD, however, because the other nine cases who showed normal thickness and normal SI of ACL on MRI also showed MD in pathology, normal MRI finding should not exclude the possibility of MD of ACL.

• Journal of Korean Medicine Rehabilitation
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• v.19 no.1
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• pp.135-143
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• 2009

Objectives : Low back pain(LBP) is a common disabling disease in clinical practice and loss of working hours due to this condition is huge. The aim of this study was to determine if there was an association between fat deposit of paraspinal muscles as observed on MRI scans in patients presenting with unilateral LBP. Methods : 24 patients who visiting our hospital with a clinical presentation of unilateral LBP were recruited to the study. Patients were between 20 and 30 years and had a history of unilateral LBP within 12 months. After MRI scaning, the images were saved in DICOM file format for Picture Archiving and Communication System(PACS). The percentage of fat infiltrated area was measured using a pseudocoloring technique. Data were analyzed comparing the fat deposits of the muscles on the symptomatic and asymptomatic sides. Paired t-test was used to find the difference between the measurements of fat tissue in individual patients. Results : The amount of fat in the symptomatic side was $7.6{\pm}4.51%$, asymptomatic side was $6.7{\pm}4.29%$. There were increases, statistically significant, in the fat changes of the paraspinal muscles at the L4-5 disc level(P <0.05). Also, men were likely than women to have more fat deposit in symptomatic side(men $8.5{\pm}5.1%$, women $6.5{\pm}3.6%$). Conclusions : The amount of fat in the symptomatic side shows significantly increased than asymptomatic side in the paraspinal muscles at the L4-5 disc level. It suggested that fat infiltration in the muscles associated with LBP. Further studies will be needed to confirm the relationship between the muscle fatty changes and LBP in the large sample size. In addition, the correlation of pain severity with fat infiltration needs to be addressed.